The invention relates to a device for conditioning the lubricating oil of a torque transmission device for motor vehicles of the introductory portion of claim 1.
Motor vehicle transmissions and differentials are lubricated at the front axle as well as at the rear axle by means of oils, especially transmission oils. The oil has different tasks here: partly, it is used to activate control elements for the transmission of force (torque converters), for lubricating mutually contacting tooth flanks and for transporting heat within the transmission. The oils wet the metallic surfaces and the corresponding contact surfaces of the gear pairings in the transmission. By these means, cold welding of the contact surfaces is prevented. Accordingly, it is important to bring sufficient oil to the corresponding mutually contacting tooth flanks. For oil bath-lubricated transmissions, one or more gearwheels is/are in the so-called oil sump. With the combing of gear wheels in this oil sump, oil is conveyed and, in this way, reaches the mutually contacting tooth flanks. Due to the meshing of the gear wheels in the oil and due to oil squeezing losses, churning losses occur here in the regions, in which the different gear wheels mesh. This is caused by oil being pushed away at the tooth flanks and the interstices of the teeth.
The DE 10 2008 057 510 A1 discloses a generic device, for which the transmission oil of a change-speed gearbox with an integrated differential is heated in order to reduce the frictional and churning losses of the transmission element, particularly in the cold state of the transmission oil. The ring-shaped heating element is disposed about the gear shaft in such a manner, that it protrudes partly into the oil sump of the transmission and, in addition, is wetted by the oil sprayed by an adjacent gear wheel. As with other known devices, the most efficient heating effect is intended to heat all of the transmission oil in the oil sump.